Bifurcated drawing instrument



May 19,v 1936.

Filed Dec. 9, 1933 Flea.

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R om TY NA E VM NU .IE N .D R A U D En UNITED N STATES PATENT OFFICE- `2,041,299 V BIrURcA'rED DRAWING INSTRUMENT Eduard Neumayer, Pfronten-Ried, Germany, as-

signor toKeuffel & Esser Co., Hoboken, N. J., a corporation of New Jersey Application December 9, 1933, Serial No. 701,578

In Germany January 13, 1933 2 Claims.

'I'his invention relates to bifurcated drawing instruments, such as dividers and compasses, of the kind in which a pair of legs are provided at their extremities with points. Dividers have needle points on each leg and Compasses have a needle point on one leg and, on the other leg, an insertion piece, either a pencil point or a pen point or in some instances, a needle point whereby the compass may serve as a divider.

As the spacing of the divider or compass points is a function of the lengths of the legs as Well as a function of their angular relation and as the draughtsman usually attainsthe desired angular relation of the legs by manipulating the legs with his fingers, difficulty is experienced, particularly by the inexpert, in making minute adjustments. SomeV Compasses are,` therefore, provided with a so-called hair-spring but the addition of a hair-spring to any instrument lof this type necessitates the highest quality in design and workmanship, and, moreover, the hairspring does not satisfactorily correct the differences in the relative length of the legs as, say, when a needle point is Worn down or where a pencil point varies in lengthduring use.

'Ihe present invention has for its primary object to obviate these difliculties. In accordance with the invention mechanicalmeans are provided fo-r varying the length of at least one leg of a bifurcated drawing instrument whereby the distance between the two points, or the length of the respective legs, may be exactly that' desired.

Another object of theinvention is adjustable meansfor advancing and retracting a carrying device for a point such as a needle point or pencil point, as desired. Y

The invention also seeks a drawing instrument of the character described which is practical from the standpoint of ease and cheapness of manufacture and convenience, precision and durability in use.

These and other objects of the invention and the means for their attainment will be more apparent from the following detailed description, taken in connection with the accompanying drawing illustrating one embodiment by which the invention may be realized, and in which:

Figure 1 is a view showing the invention applied to a compass;

Figure 2 is a fragmentary view showing an adjustable point for one leg of a divider or compass, parts being in elevation and parts being sectioned on the line 2-2 of Figure 1;

Figure 3 is a view of the same operating parts shown in Figure 2, but for a lead point and sectioned in a longitudinal that of Figure 2; and

Figure 4 is a transverse sectional view taken on the line 4-4 of Figure 2. j

While the invention, for convenience, has been- 5 illustrated as appliedV to both legs of the compass shown in Figure 1, in order to demonstrate two uses of the invention, it will be obvious that an adjustable point may be disposed on one leg of a divider of any desired type, the other leg 10 of which is of constant'length or both legs of the divider may be adjustable in length, as desired. Similarly, a pencil point may be so'mounted in one leg of a compass as to be advanced and retracted to dispose its point at a desired 15 distance from the pivoted joint inthe head while the length of the other leg may be either fixed or adjustable.

In the illustrated embodiment, the type of compass shown comprises the fork 6 upon which the two legs 8 and I 0 are pivotally mounted. 'I'he leg 8 may or may not be provided with a knee joint I2 and similarly the insertion piece I4 may or may not be provided with a knee joint I6, 'these parts being illustrated merely to show the applicability to any required type of instrument. The insertion piece I4 may have the usual shank, not shown, for reception in the recess formed in the extremity of leg I0, and secured, as is usual, by the set screw I8. 30

Inorder that the description may apply to eitherv a divider or compass irrespective of whether the improved extremity of the leg is formed by an insertion piece or not, the extremf, ity of the leg of any bifurcated drawing instru- 35 ment will be represented generally by the part numbered 20.

Extending from the extremity 20 is an inner tubular sleeve 22 preferably longitudinally slotted on diametrically opposite sides, as at 24. The sleeve 22 is smaller in diameter than the leg 2U so that a shoulder 2| is formed. Within the sleeve 22 reciprocates a carrier member substantially cylindrical in shape. VFor use with a needle point, the carrier 26, Figure 2, is formed with av threaded recess 21 in its lower end adapted to receive the threaded inner end of the needle 28. For use with a compass, as a pencil point, the carrier 30, Figure 3, is tubular and is slotted-as at 3| whereby 'it may expand to receive and grip 50 a lead 32.

The axial slots 24 in the tubular inner sleeve 22 form ways by which the carrier is retained plane perpendicular to against axial rotation While its reciprocation is permitted. The carrier may be formed with or 55 otherwise carry a guide member 36 conveniently formed as a flat plate extending in a diametric plane from the inner end of the carrier. This plate is conveniently of a thickness so that its side edges may be received and guided in the slots 24 and the peripheral surfaces are formed with related threads 38 to function as a mutilated nut.

To cause the reciprocation of the carrier (26 or 30), an internally threaded operating or outer sleeve 40 is telescoped over the inner slotted sleeve 22 and is freely rotatable thereabout. For convenience in its manipulation, the surface of the sleeve is irregular, in this instance, the shape is polygonal. The internal threads engage the nut 36, 38 so that, as the sleeve is rotated in one direction, the carrier is caused to move axially of the leg toward the head to retract the needle point or lead and when the sleeve is rotated in the opposite direction, the carrier is moved toward the extremity to advance the needle point or lead. The sleeve i0 is retained on the inner sleeve 22 in abutting relation with the shoulder 2| on the leg 20 by a frusto-conical tip or end 42 forming a shoulder on the lower end of the leg which abuts against sleeve 40. The sleeve rotates between these shoulders. The tip @2 has an axial bore to permit the rod like member 28 or 32 to pass therethrough and be guided therein as a bearing. Its inner end is internally threaded, as at 43, for engagement with the externally threaded end 44 of the inner sleeve 22, which end is of a diameter less than the inner diameter of the sleeve 40 so that the latter may pass freely thereover.

To facilitate assembly, the inner sleeve 22 near its lower threaded end 44 is conveniently cut away to provide an enlarged opening 46 into which a slot 24 opens. Through this opening the carrier may be inserted and removed.

It will thus be seen that the length of either or both legs of a bifurcated drawing instrument may be varied at will to permit minute adjustments of the points either as to their spacing in the exact measurement of distances or as to their relative length in order, for instance, that the extremities of the needle point and the point on the other leg will meet. The lead holding device of this invention has the advantage over lead points heretofore known in that thin leads may be used since they are not subject to a clamping pressure and, therefore, do not tend to break at the point of clamping. In case the point wears off or breaks it can easily be readjusted to the desired position by rotating the operating sleeve. A further advantage is that the lead can be screwed back into the holding device when the instrument is not in use so that the point is protected from injuries. The invention also serves as a micrometer adjustment for the points since by changing the adjustment, the length of the compass leg, and consequently the radius, is changed.

Various modifications will occur to those skilled in the art in the form taken by the adjustable mountings for the points as well as in the application thereof to drawing instruments of various kinds and types and no limitation is intended by the phraseology of the foregoing description or illustrations in the accompanying drawing.

What is claimed is:-

1. A bifurcated drawing instrument comprising, in combination, a pair of relatively movable legs, a tubular sleeve threaded at its outer end and carried axially of a leg in prolongation thereof and of a smaller diameter than the leg and formed with a pair of diametrically disposed axially extending slots, a carrier for a needle, lead or the like reciprocable within the sleeve, a guide member carried with the carrier and passing through the slots, the exposed portions of the guide member being formed with related threads, an internally threaded operating sleeve telescoped over the innercsleeve and freely rotatable thereabout and in threaded engagement with the threads on the carrier guide and a tipof an outside diameter greater than the inner sleeve and threaded on the end thereof to retain the operating sleeve thereon.

2. In a bifurcated drawing instrument, an arm, an inner tubular sleeve xed to the arm at its extremity and longitudinally slotted on diametrically opposite sides, said sleeve being of a diameter less than the extremity to form a shoulder, a substantially cylindrical carrier member reciprocating within the sleeve adapted to receive a needle, a lead or the like, a fiat plate-like guide member carried with the carrier and extending in a diametric plane within the slots in the sleeve, the peripheral surfaces of which are formed with related threads, an outer sleeve surrounding the inner sleeve formed with threads on its inner surface adapted to engage with the threads on the guide member and a tip formed with an axial bore threaded on the lower end of the inner sleeve to retain the outer sleeve in position.

EDUARD NEUMAYER. 

